Models SST120 and SST240 auxiliary function modules gradually apply power to the load when energized by the control voltage. They must be used with Crydom Series 1 (-10) random turn-on solid state relays. Consult factory about use with 480 Vac loads. For a complete set (control module and solid state relay) order 10SST120, 25SST120, etc. Manufactured in Crydom's ISO 9002 Certified facility for optimum product performance and reliability.